This invention relates generally to the field of underwater breathing apparatus for divers, and more particularly to a heated sheath device for improving the operation and duration and comfort in use of diving apparatus of the type comprising a CO.sub.2 (carbon dioxide) scrubbing cannister, one or more breathing bags, and flexible hoses for conducting breathing gas between the diver and the breathing bag or bags.
Diving apparatus of the foregoing type, usually of closed or semiclosed circuit configuration, suffer from considerable heat loss when operated at considerable depths (such as require a mixed gas breathing medium) and water temperatures of, say, 30.degree. F. Inasmuch as efficient CO.sub.2 scrubbing is dependent on favorable conditions of temperature and humidity, the results of the heat loss, experienced largely by conduction of thermal energy through the breathing bag walls, hose walls, and scrubber cannister to surrounding water, are manifested in diver discomfort and in shortened dive duration because of the CO.sub.2 absorbent bed not being fully used.
Heat losses from the cannister walls have been offset through the use of a water heated cannister described in U.S. Patent Application, Ser. No. 06/227,285, filed Jan. 22, 1981, and assigned to the assignee hereof. The heat losses through the breathing bag and hose walls are addressed by this invention.